Arthroscopic Findings After Osteochondral Allografts of the Knee: Proposed Classification Scheme and Associations With Graft Failure

Abstract

Background:

Limited studies exist on the gross appearance of osteochondral allografts (OCAs) at the time of second-look arthroscopy to determine whether the graft and adjacent cartilage have signs of degeneration contributing to failure.

Purpose:

To describe the gross appearance of OCAs and the adjacent cartilage at the time of a second-look knee operation to help propose an accurate definition of structural and clinical OCA failure and to standardize and classify the intraoperative findings associated with structural graft failure.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review was conducted on all patients who underwent knee OCA transplantation and a subsequent procedure with graft visualization. At second look, grafts were classified using intraoperative imaging and operative reports as nonfailing or failing, with structural failure defined as grade 3 or 4 OCA degeneration (Outerbridge classification system) or moderate-to-severe (>2 mm) peripheral chondral delamination. The status of cartilage adjacent to the graft, including degeneration and delamination, was recorded. Patient characteristics, surgical factors, and graft and cartilage characteristics were evaluated for associations with functional outcomes and subsequent reconstruction (revision OCA, unicompartmental knee arthroplasty, or total knee arthroplasty). Functional outcomes were assessed using the International Knee Documentation Committee, the Osteoarthritis Outcome Score for Joint Replacement, and the Veterans RAND 12-Item Health Survey from index transplantation to the second-look procedure.

Results:

Of 1152 OCAs performed, 129 grafts (11.2%) from 127 patients underwent a subsequent procedure for symptomatic patellofemoral pathology that included a second-look evaluation at a mean of 2.20 ± 2.06 years. A total of 42 grafts (32.6%) were classified as demonstrating structural graft failure at a mean of 3.17 ± 2.17 years. Structural failure was attributed to graft degeneration (81%) and chondral delamination (21%). Significant cartilage damage adjacent to the OCA border was present in 13 nonfailing grafts (14.9%) and 17 failing grafts (40.5%). Concomitant procedures at index surgery were predictive of structural success (P = .0044), whereas patients with more previous procedures were more likely to experience structural failure (P = .0319). At a mean of 3.14 years from the index OCA, revision reconstruction was performed in 42.9% of patients with structural failure, compared with 9.2% without structural failure. Structural failure classification at second look was strongly correlated with clinical failure (P < .00001).

Conclusion:

Clinical failure after OCA transplantation appears to be multifactorial. Characterization of macroscopic graft morphology may help surgeons better define clinical and structural failure of OCA transplantation. Future study is required to evaluate the influence of adjacent cartilage and the factors associated with this finding.